Theory of electric-field-induced spin accumulation and spin current in the two-dimensional Rashba model

Abstract

Based on the spin-density-matrix approach, both the electric-field-induced spin accumulation and the spin current are systematically studied for the two-dimensional Rashba model. Eigenmodes of spin excitations give rise to resonances in the frequency domain. Utilizing a general and physically well-founded definition of the spin current, we obtain results that differ remarkably from previous findings. It is shown that there is a close relationship between the spin accumulation and the spin current, which is due to the prescription of a quasi-chemical potential and which does not result from a conservation law. Physical ambiguities are removed that plagued former approaches with respect to a spin-Hall current that is independent of the electric field. For the clean Rashba model, the intrinsic spin-Hall conductivity exhibits a logarithmic divergency in the low-frequency regime.

Kinetic theory of spin-polarized systems in electric and magnetic fields with spin-orbit coupling. I. Kinetic equation and anomalous Hall and spin-Hall effects

“…Please note that the universal constant in (159) is necessary to obtain the correct small spin-orbit coupling result where the definition of spin current has been employed in terms of physical argumentation. Again the result here differs from the resonant structure found in 122 by the arctan term but the static limit agrees with the result of 6,124 . The dynamical result (159) describes the influence of an external magnetic field as well as mean magnetizations due to magnetic impurities.…”

“…This dynamical result is different from the spin accumulation found in 122 basically by the arctan term and therefore no sharp resonance feature. Expanding, however, in small spin-orbit coupling shows that the static limit agrees with 122,123 . Please note that if one sets Σ n → 0 before expanding a factor 1/2 appears which illustrates the symmetry breaking by the effective Zeeman term.…”

Spin polarization in biased Rashba-Dresselhaus two-dimensional electron systems

“…20 From this set of equations, spin-charge coupled drift-diffusion equations are derived for the physical components f = Tr f and f = Trσ f , which are integrated over the polar angle of k (denoted by the bar). In the case of weak SOI (αk F τ / , βk F τ / ≪ 1, with k F and τ being the Fermi wave vector and elastic scattering time, respectively), the following ansatz is justified 21…”

Electric-field induced spin textures in a superlattice with Rashba and Dresselhaus spin-orbit coupling

“…23 The spin-related quantity which can actually be probed by a tip in the experiment or possibly utilized in a spintronic nanostructure device is the local spin density in a real space, which manipulation is one of the primary goals of spintronics. The local change of the spin density is often referred to the conception of a spin current which permanently attracts a considerable attention of researchers 12,24,34,35,36 (only few papers from a great number of published articles on the spin current are cited here as an example), and where the different definitions have been proposed. Taking into consideration the goals of the present paper, one should mention that the experimental studies of the spin current phenomena are presently focused on the observation of spin accumulation.…”